Re: [PATCH net-next + leds v2 6/7] net: phy: marvell: add support for LEDs controlled by Marvell PHYs

From: Andrew Lunn
Date: Fri Sep 11 2020 - 08:49:46 EST

> - Do all PHYs support manual setting of the LED level, or are the PHYs
> that can only work with HW triggers?

There are PHYs with do not have simple on/off.

> - Is setting PHY registers always efficiently possible, or should SW
> triggers be avoided in certain cases? I'm thinking about setups like
> mdio-gpio. I guess this can only become an issue for triggers that
> blink.

There are uses cases where not using software frequently writing
registers would be good. PTP time stamping is one, where the extra
jitter can reduce the accuracy of the clock.

I also think activity blinking in software is unlikely to be
accepted. Nothing extra is allowed in the hot path, when you can be
dealing with a million or more packets per second.

So i would say limit software fallback to link and speed, and don't
assume that is even possible depending on the hardware.